Statistical assessment of proton treatment plans under setup and range uncertainties

Peter C. Park, Joey P. Cheung, X. Ronald Zhu, Andrew K. Lee, Narayan Sahoo, Susan L. Tucker, Wei Liu, Heng Li, Radhe Mohan, Laurence E. Court, Lei Dong

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Purpose: To evaluate a method for quantifying the effect of setup errors and range uncertainties on dose distribution and dose-volume histogram using statistical parameters; and to assess existing planning practice in selected treatment sites under setup and range uncertainties. Methods and Materials: Twenty passively scattered proton lung cancer plans, 10 prostate, and 1 brain cancer scanning-beam proton plan(s) were analyzed. To account for the dose under uncertainties, we performed a comprehensive simulation in which the dose was recalculated 600 times per given plan under the influence of random and systematic setup errors and proton range errors. On the basis of simulation results, we determined the probability of dose variations and calculated the expected values and standard deviations of dose-volume histograms. The uncertainties in dose were spatially visualized on the planning CT as a probability map of failure to target coverage or overdose of critical structures. Results: The expected value of target coverage under the uncertainties was consistently lower than that of the nominal value determined from the clinical target volume coverage without setup error or range uncertainty, with a mean difference of -1.1% (-0.9% for breath-hold), -0.3%, and -2.2% for lung, prostate, and a brain cases, respectively. The organs with most sensitive dose under uncertainties were esophagus and spinal cord for lung, rectum for prostate, and brain stem for brain cancer. Conclusions: A clinically feasible robustness plan analysis tool based on direct dose calculation and statistical simulation has been developed. Both the expectation value and standard deviation are useful to evaluate the impact of uncertainties. The existing proton beam planning method used in this institution seems to be adequate in terms of target coverage. However, structures that are small in volume or located near the target area showed greater sensitivity to uncertainties.

Original languageEnglish (US)
Pages (from-to)1007-1013
Number of pages7
JournalInternational Journal of Radiation Oncology Biology Physics
Volume86
Issue number5
DOIs
StatePublished - Aug 1 2013
Externally publishedYes

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Uncertainty
Protons
dosage
protons
lungs
brain
planning
Prostate
cancer
proton beams
histograms
Brain Neoplasms
standard deviation
brain stem
range errors
deviation
esophagus
rectum
spinal cord
Lung

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Radiation
  • Cancer Research

Cite this

Statistical assessment of proton treatment plans under setup and range uncertainties. / Park, Peter C.; Cheung, Joey P.; Zhu, X. Ronald; Lee, Andrew K.; Sahoo, Narayan; Tucker, Susan L.; Liu, Wei; Li, Heng; Mohan, Radhe; Court, Laurence E.; Dong, Lei.

In: International Journal of Radiation Oncology Biology Physics, Vol. 86, No. 5, 01.08.2013, p. 1007-1013.

Research output: Contribution to journalArticle

Park, PC, Cheung, JP, Zhu, XR, Lee, AK, Sahoo, N, Tucker, SL, Liu, W, Li, H, Mohan, R, Court, LE & Dong, L 2013, 'Statistical assessment of proton treatment plans under setup and range uncertainties', International Journal of Radiation Oncology Biology Physics, vol. 86, no. 5, pp. 1007-1013. https://doi.org/10.1016/j.ijrobp.2013.04.009
Park, Peter C. ; Cheung, Joey P. ; Zhu, X. Ronald ; Lee, Andrew K. ; Sahoo, Narayan ; Tucker, Susan L. ; Liu, Wei ; Li, Heng ; Mohan, Radhe ; Court, Laurence E. ; Dong, Lei. / Statistical assessment of proton treatment plans under setup and range uncertainties. In: International Journal of Radiation Oncology Biology Physics. 2013 ; Vol. 86, No. 5. pp. 1007-1013.
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AU - Tucker, Susan L.

AU - Liu, Wei

AU - Li, Heng

AU - Mohan, Radhe

AU - Court, Laurence E.

AU - Dong, Lei

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N2 - Purpose: To evaluate a method for quantifying the effect of setup errors and range uncertainties on dose distribution and dose-volume histogram using statistical parameters; and to assess existing planning practice in selected treatment sites under setup and range uncertainties. Methods and Materials: Twenty passively scattered proton lung cancer plans, 10 prostate, and 1 brain cancer scanning-beam proton plan(s) were analyzed. To account for the dose under uncertainties, we performed a comprehensive simulation in which the dose was recalculated 600 times per given plan under the influence of random and systematic setup errors and proton range errors. On the basis of simulation results, we determined the probability of dose variations and calculated the expected values and standard deviations of dose-volume histograms. The uncertainties in dose were spatially visualized on the planning CT as a probability map of failure to target coverage or overdose of critical structures. Results: The expected value of target coverage under the uncertainties was consistently lower than that of the nominal value determined from the clinical target volume coverage without setup error or range uncertainty, with a mean difference of -1.1% (-0.9% for breath-hold), -0.3%, and -2.2% for lung, prostate, and a brain cases, respectively. The organs with most sensitive dose under uncertainties were esophagus and spinal cord for lung, rectum for prostate, and brain stem for brain cancer. Conclusions: A clinically feasible robustness plan analysis tool based on direct dose calculation and statistical simulation has been developed. Both the expectation value and standard deviation are useful to evaluate the impact of uncertainties. The existing proton beam planning method used in this institution seems to be adequate in terms of target coverage. However, structures that are small in volume or located near the target area showed greater sensitivity to uncertainties.

AB - Purpose: To evaluate a method for quantifying the effect of setup errors and range uncertainties on dose distribution and dose-volume histogram using statistical parameters; and to assess existing planning practice in selected treatment sites under setup and range uncertainties. Methods and Materials: Twenty passively scattered proton lung cancer plans, 10 prostate, and 1 brain cancer scanning-beam proton plan(s) were analyzed. To account for the dose under uncertainties, we performed a comprehensive simulation in which the dose was recalculated 600 times per given plan under the influence of random and systematic setup errors and proton range errors. On the basis of simulation results, we determined the probability of dose variations and calculated the expected values and standard deviations of dose-volume histograms. The uncertainties in dose were spatially visualized on the planning CT as a probability map of failure to target coverage or overdose of critical structures. Results: The expected value of target coverage under the uncertainties was consistently lower than that of the nominal value determined from the clinical target volume coverage without setup error or range uncertainty, with a mean difference of -1.1% (-0.9% for breath-hold), -0.3%, and -2.2% for lung, prostate, and a brain cases, respectively. The organs with most sensitive dose under uncertainties were esophagus and spinal cord for lung, rectum for prostate, and brain stem for brain cancer. Conclusions: A clinically feasible robustness plan analysis tool based on direct dose calculation and statistical simulation has been developed. Both the expectation value and standard deviation are useful to evaluate the impact of uncertainties. The existing proton beam planning method used in this institution seems to be adequate in terms of target coverage. However, structures that are small in volume or located near the target area showed greater sensitivity to uncertainties.

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